I apologize if this has already been answered, but I'm a little confused by the graphs. Are the Home Depot 2-bulb T8 fixtures really better than most of the 2-bulb T5HO fixtures in the graph above it?

The chart shows that the diamond plate, 2 bulb, T8, Home Depot shop light gives about 70-75 micromols of PAR at 15 inches. The other chart, of T5 lights, shows only the Hagen Glo, Coralife and FishNeedIt 2 bulb T5HO lights give less than that, and those may have sub-standard ballasts, and do have relatively poor reflectors. I agree that it is hard to believe that the Home Depot T8 light is that good, but someone tested it and that was where the data came from. I also measured the PAR at one distance for one, at a local aquatic plant club meeting, and the reading was consistent with that chart. I saw one on a tank once, and it certainly did look very bright.